Archives de catégorie : biology+acidification

Prof Peter Ridd: the Great Barrier Reef recovers, our science institutions are failing us, science needs to be checked

by Alan Jones, interviews peter Ridd, July 28,  2017 in JoNova

Corals have a little thermometer built in them, when you take a core of them from many years ago we know what the temperature of the water was back when Captain Cook sailed up the coast, it was actually about the same temperature then. It was colder 100 years ago, but it has recovered from that. The temperatures on the reef are not even significantly warmer than average on a hundred year timescale.

Corals that bleach in one year will be less susceptible to bleaching in following years

‘Perfect storm’ led to 2016 Great Barrier Reef bleaching

by James Cook University and Université Catholique de Louvain, July 3, 2017, in ScienceDaily

Professor Wolanski said the study was subjective to the extent that there was a lack of oceanographic field data in the Great Barrier Reef itself for the 2016 el Nino event. By contrast, the amount of oceanographic field data in the Torres Strait and the northern Coral Sea was very good.

« What we presented is our best-informed attempt to reveal the mechanisms involved in causing the event, based on the available oceanographic data combined with the existing body of knowledge on the water circulation in and around the Torres Strait/Northern Great Barrier Reef region. »

Indirect Positive Effects of Ocean Acidification Can Overpower Sometimes Observed Direct Negative Effects

by S.D. Connell et al., 2017 in Current Biology (in CO2 Science)

The increasing absorption of CO2 and associated decline in seawater pH values is thought to pose direct harm to marine life in the decades and centuries to come by affecting rates of survival, calcification, growth, development and/or reproduction. However, as ever more pertinent evidence accumulates, a much more optimistic viewpoint is emerging.

Densely Aggregated Corals Maintain Calcification Under Ocean Acidification Conditions

by N.R. Evensen and P.J. Edmunds, 2017, J. Exp. Biology

Regardless of the actual mechanism responsible for the densely aggregated corals to maintain calcification rates in the face of ocean acidification, the study of Evensen and Edmunds, in their words, offers « a compelling case for differential densities of branching coral colonies (i.e. aggregation types) mediating the sensitivity of coral communities in at least some habitats » and it further supports « recent indications that neighboring organisms, such as conspecific coral colonies in the present example, can create small-scale refugia from the negative effects of ocean acidification » And that is more good news for those concerned about the future health of these important marine ecosystems.

Stony corals more resistant to climate change than thought

by Rutgers University, June1, 2017 in SienceDaily

Stony corals may be more resilient to ocean acidification than once thought, according to a Rutgers University study that shows they rely on proteins to help create their rock-hard skeletons.

« The bottom line is that corals will make rock even under adverse conditions, » said Paul G. Falkowski, a distinguished professor who leads the Environmental Biophysics and Molecular Ecology Laboratory at Rutgers University-New Brunswick. « They will probably make rock even as the ocean becomes slightly acidic from the burning of fossil fuels. »

See also here

L’acidification des océans : causes anthropiques versus variabililité naturelle

Usbek, 13 avril 2017

L’acidification n’est pas une simple réponse statique à l’augmentation de la concentration de CO2 dans l’atmosphère : c’est la résultante de processus biologiques et physico-chimiques qui entraînent une répartition inégale du carbone sur la verticale de l’océan. D’autre part la vie océanique a survécu à des niveaux beaucoup plus élevés de CO2 depuis des millions d’années dans le passé.